As a type of memory element using a magnetoresistive effect element, a magnetic random access memory (MRAM) element having a magnetic tunnel junction (MTJ) structure has attracted attention. The MRAM element includes a multilayer film formed of a hard-to-etch material containing a metal such as, for example, a ferromagnetic material. In a step of manufacturing such an MRAM element, the multilayer film is etched using a mask formed of a metal material such as, for example, tantalum (Ta) or TiN.
In such etching, a halogen gas has been used in the art as described in Patent Document 1. The manufacturing method disclosed in Patent Document 1 is a method of manufacturing a semiconductor device, which includes a step of forming a magnetoresistive effect element using a magnetic material including at least one of cobalt, iron, and nickel. The step of forming the magnetoresistive effect element includes a step of forming a laminate including a plurality of layers containing a magnetic material on a semiconductor substrate, a step of processing the laminate by plasma etching using a gas containing chlorine in a vacuum atmosphere, and a step of performing a gas processing on the laminate using a gas containing an amino group while keeping the laminate in a vacuum atmosphere after processing the laminate.